If your machine is on a private IP segment (10.x.x.x or 192.168.x.x) then there's a NAT gateway/firewall between your machine and the internet proper and you can't directly SSH in from outside. You have to configure an explicit port redirection on the gateway machine/router to do it.

If your machine is on a private IP segment (10.x.x.x or 192.168.x.x) then there's a NAT gateway/firewall between your machine and the internet proper and you can't directly SSH in from outside. You have to configure an explicit port redirection on the gateway machine/router to do it.

Maybe use dyndns and redirect ssh over a more common http (or something port)? That would simplify getting into your Z from different networking environments, especially those where you can't eaily do the port redirection on the NAT, wouldn't it?You'd probably want to be running a firewall on the Z and of course edit yuor hostname and sshd.conf, right? Or had you already considered this option?